I'm trying to create this model for 3d printing. Blender says I have zero faces even though they have area. How do I fix this?
I believe that is telling you there are zero area faces present, and that tool will  highlight them if you click on the actual button that is reporting them . You can probably simply delete the faces it has highlighted and all will be well.
Maybe a better approach would be to select all of the faces in the object (in edit mode) and then go to Mesh -&gt; Clean Up -&gt; Degenerate Dissolve, which will dissolve all zero area faces and zero length edges ....